By JONATHAN WEISMAN

January 9, 2014

WASHINGTON — With his strong-armed change to the filibuster rule and an iron-fisted control of the Senate floor, Senator Harry Reid has engaged in the greatest consolidation of congressional power since Newt Gingrich ruled the House, unleashing a bitterness that may derail efforts to extend unemployment insurance.

Mr. Reid of Nevada, the majority leader, on Thursday dismissed all proposed Republican amendments to the unemployment extension, even those drafted by Republicans who had handed Democrats a victory on Tuesday by voting to take up the bill.

“We get nowhere with dueling amendments,” Mr. Reid declared.

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A Republican effort to try to reopen the amendment process failed on a party-line vote, 42 to 54, setting up a showdown next week that is likely to end in the bill’s demise, Democrats conceded.

To Democrats, it was a typical Reid show of force in the face of unfair Republican amendments. To Republicans, it was only the latest — and one of the boldest — slaps in the face.

“I’m just kind of fed up,” said Senator Lisa Murkowski of Alaska, a moderate Republican who has increasingly become a key vote for Democratic legislation. “He’s a leader. Why is he not leading this Senate? Why is he choosing to ignore the fact that he has a minority party that he needs to work with, that actually has some decent ideas? Why is he bringing down the institution of the Senate?”

Mr. Reid’s brutish style matters beyond the marbled chamber of the Senate. Senate legislation has increasingly turned into a battle over amendments and Mr. Reid’s uncompromising control over the process. The six Republicans who voted to take up the unemployment bill on Tuesday expected at least to be allowed votes on their amendments to shape the legislation.

Instead, Mr. Reid dismissed all Republican proposals as unacceptable and then proposed his own new unemployment deal. Under it, benefits would be extended until mid-November of this year, and paid for largely by extending a 2 percent cut to Medicare health providers in 2024. Republicans were outraged, and an obscure procedural fight is likely to leave up to three million out-of-work Americans without benefits.

“We need to be able to have votes on behalf of our states,” said Senator Kelly Ayotte, Republican of New Hampshire, who was denied a vote on her amendment to pay for the extension by requiring applicants for the child tax credit to have Social Security numbers, a proposal Mr. Reid declared an attack on children. “I don’t know what the issue is, unless you are afraid it will pass.”

Ms. Murkowski said that she was unlikely to support the bill.

The unemployment bill is only the most recent example of legislation that has become stuck in a procedural quagmire, affecting senators in both parties. A long-awaited showdown between two Democratic senators, Kirsten E. Gillibrand of New York and Claire McCaskill of Missouri, over the military’s approach to sexual assault fizzled late last year when they were denied any votes on an annual military policy bill that usually is shaped over weeks on the Senate floor. A bipartisan bill on Iran sanctions has yet to receive floor consideration. And Democrats, eager to replace a tax on medical devices that helps pay for the Affordable Care Act, have been denied a vote.

“I would like to take one of the bipartisan bills and allow for a more open amendment process,” said Senator Amy Klobuchar, Democrat of Minnesota and a primary sponsor of the medical device tax repeal. “I think that would be a good way to do it and more forward.”

For their part, Republicans have received all of four amendment votes since mid-July.

Rankled by the Republican criticism, Mr. Reid said in an interview that Republicans refused to agree to any reasonable limit on amendments despite his overtures.

“So we get nothing done, which is their goal anyway,” Mr. Reid said.

He accused Republicans of instigating attacks on him to shift attention from the impasse over unemployment benefits.

“This is a very difficult issue for them,” Mr. Reid said about the politics of the aid to the jobless.

The bitterness burst into the open on Wednesday afternoon. With virtually all of his Republican colleagues watching, Senator Mitch McConnell of Kentucky, the minority leader, took to the Senate floor to deliver a nearly hourlong lament about the destruction that Mr. Reid has wrought, describing the Senate as a post-apocalyptic wasteland ruled by a dictatorial autocrat despised by allies and foes alike. He compared Mr. Reid’s leadership to the famously strong-armed style of Lyndon B. Johnson when he was Senate majority leader in the 1950s, not a compliment in Mr. McConnell’s account.

The only Democrat to show up was the freshman senator tasked to sit in the leader’s chair. And Mr. Reid, who has led the Senate since 2007, watched the show on television from his office suite a few yards away.

In the struggle to define Mr. Reid’s leadership, each side has crunched statistics and studied history to prove its point. Aides to Mr. Reid say in no way has he mistreated the Republican minority. In his time as leader, he has allowed votes on almost 95 Republican amendments a year, 75 percent of the total. That is fewer than former Senator Bill Frist of Tennessee gave Democrats when he was majority leader — 117, or 76 percent — but more than Senator Trent Lott of Mississippi gave minority Democrats, 90 votes a year, 54 percent of the total.

“I have been very generous with amendments,” Mr. Reid said.

But Republicans argue that few could say the Senate is functioning. Compared with 2011, the Senate saw a 20-percent decline in bills approved last year, and senators cast the second-lowest number of votes of any first session this century. Democrats say Republicans were given 74 amendment votes last year, 68 percent of the total. But half of them came over one grueling 24-hour marathon, when the Senate voted on 37 nonbinding advisory amendments to the Senate budget last spring.

Absent those votes, Republicans were given 37 votes last year, 51 percent of the total. And Senate votes are trending downward. Exempting nonbinding budget amendments, total amendment votes reached 218 in 2007, Mr. Reid’s first year in control, to 175 in 2009, to 123 in 2012, to 67 last year, by Reid staff calculations. Since mid-July, Republicans have gotten four amendment votes.

Reid aides accept that power has drastically concentrated in Mr. Reid’s office, but counter that is because of the unprecedented obstruction by Republicans to derail President Obama. Dueling with Senator Dan Coats, Republican of Indiana, Mr. Reid made the case that “every amendment offered, with rare exception, is a gotcha amendment,” adding, “That isn’t what we do here.”